Visualization of unevenly-spaced time series data

Just quickly, does anyone know of any good (easy to use) tools for visualizing unevenly-spaced time series data? I really don't want to do anything more fancy than create a line/point chart, but the chart should take the uneven spacing of the data into account and display it accordingly.

FOSS would be preferrable, but anything free will be OK. Barring that, if somebody's got access to a non-free tool and can help me with this (I'd send the data and an example of the kind of chart I'd want), that'd be fine, too.